System and method for monitoring tension of chain of scraper conveyor
Technical Field
The invention relates to the technical field of scraper conveyor monitoring and safety guarantee, in particular to a scraper conveyor chain tension monitoring system.
Background
The scraper conveyor is the main production transportation equipment of the fully mechanized working face under the coal mine, and undertakes the important tasks of transporting coal, providing a pushing fulcrum for a hydraulic support and providing a walking track for a coal mining machine, and the reliability of the scraper conveyor directly influences the safety and the benefit of the modern coal mine production.
The scraper chain (scraper, ring chain and chain connector) of the scraper conveyor has the functions of dragging, guiding, transmitting power and pushing coal, and is one of the key parts for determining the normal operation of the scraper conveyor. In the operation process of the scraper conveyor, due to the polygonal effect of a chain transmission system, frequent starting or stopping when the scraper conveyor is fully loaded or overloaded, and abnormal load effects such as caving of coal wall caving and coal wall collapse, the circular chain has vibration and impact characteristics, once tension is too large or too small, phenomena such as chain breakage, chain loosening and chain accumulation can occur, and according to statistics, 41.5% of scraper conveyor stopping is caused by chain breakage of the circular chain, and the normal production and production efficiency of a coal mine are seriously influenced. Meanwhile, the scraper conveyor runs under the working conditions of severe environments such as high temperature, humidity, top plate water spraying, dust and the like for a long time, and the invention is of great importance for the online tension monitoring technology of the round-link chain capable of working in the severe environments.
Current systems for monitoring the tension of a flight conveyor chain are: the Chinese patent with application number 201410060754.6, a tension detection device of a scraper conveyor, adopts a mode of punching a groove on the upper side of a chain and placing a sensor to monitor the tension of the chain in real time; the chinese patent with application number 201532274U, "tension measuring device for scraper conveyor chain", adopts the form of torque test wrench, mainly tests the tension of the chain of scraper conveyor when it is stationary.
The disadvantages of the above scheme are: the structure of the scraper chain is damaged, the bearing capacity of the scraper chain is reduced, chain breakage accidents are more likely to occur at the position where the sensor is placed, and safety accidents such as chain clamping and the like are more likely to occur due to the influence of the sensor when the position passes through the chain wheel; only the force in a static state can be tested, and real-time monitoring in the running process cannot be carried out. The scheme is only in a theoretical level and is not applicable to actual coal mines.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to overcome the defects in the prior art, and provides a practically-applicable nondestructive scraper conveyor chain deformation monitoring system and a stress calculation method, which can realize nondestructive monitoring of the tension of a scraper conveyor chain and effectively monitor the state of the scraper conveyor chain.
The technical scheme is as follows: in order to achieve the purpose, the invention adopts the technical scheme that:
a scraper conveyor chain tension monitoring system, the system comprising:
the terahertz imaging unit is used for detecting and scanning a scraper conveyor chain in transmission to generate a video or image signal of the chain, and comprises: the system comprises a terahertz wave transceiver, a terahertz image processing device, a support unit and a dust cover, wherein the terahertz wave transceiver is fixed on a side plate of a coal mining machine on one side above a scraper chain through the support unit, and the terahertz wave transceiver transmits acquired chain video or image signals to the terahertz image processing device;
the dust cover is arranged outside the terahertz wave transceiver and used for isolating external environment dust from the terahertz wave transceiver, a working surface made of transparent material is arranged on the dust cover, and a powder scraping mechanism is arranged on the working surface;
the dust detection sensor is used for detecting the dust amount near the dust cover in real time;
the terahertz image processing device, the dust detection sensor and the powder scraping mechanism are respectively connected with a computer through data lines.
Scrape whitewashed mechanism and include that motor, shaft coupling and L shape scrape the strip, wherein, the motor passes through the motor frame to be fixed in the outside of dust cover, and the motor output shaft passes through the shaft coupling to be connected with the one end of L shape strip of scraping, and L shape strip of scraping is contradicted with the working face external surface of terahertz wave transceiver and is connected.
The motor is a stepping motor.
The part of the L-shaped scraping strip, which is in contact with the working surface of the terahertz wave transceiver, is made of a soft material which is convenient to replace.
The soft material is soft plastic, rubber or a brush.
A monitoring method based on the scraper conveyor chain tension monitoring system comprises the following steps:
s1, selecting the scraper chain with the distance between the two scrapers to perform a tensile test on a fatigue testing machine, and measuring the force-deformation curve of the scraper chain and the deformation of the scraper chain when the scraper chain is broken S0;
s2, shooting a video of the scraper conveyor in the running process by using a terahertz imaging unit, selecting a picture at a certain interval t, identifying the distance L between two scrapers through a terahertz image processing device, and subtracting the initial distance L0 between the two scrapers to obtain the deformation S of the scraper chain;
s3, corresponding the deformation S of the scraper chain to the force-deformation curve of the scraper chain to obtain the tension F of the scraper chain, which is specifically as follows:
when S is less than 0, the scraper chain is in a loose state, and a chain tightening device of the scraper conveyor needs to be adjusted;
when S is more than or equal to 0 and less than 0.9S0, the scraper chain is in a normal working state;
when S is more than or equal to 0.9S0, the scraper chain is in a state close to fracture, and the coal conveying amount needs to be reduced in time;
the dust detection sensor transmits the detected real-time dust quantity signal to the controller, and the controller compares the real-time dust quantity signal with a preset dust threshold value, and specifically comprises the following steps:
if the real-time dust quantity signal does not exceed the maximum value of the dust threshold value, the controller controls the powder scraping mechanism to operate according to a first frequency;
and if the real-time dust quantity signal exceeds the maximum value of the dust threshold value, the controller controls the powder scraping mechanism to operate according to a second frequency, wherein the second frequency is 1.5-3 times of the first frequency.
The time t in step S2 is obtained by the following equation:
t=n*S0/(V1-V2)
wherein n is the number of the separated scrapers, V1 is the running speed of the scraper conveyor, and V2 is the running speed of the coal mining machine.
When the tension F is stable, increasing n; when the tension F fluctuates largely, n is decreased.
The step S3 in which the terahertz image processing apparatus recognizes the distance between the two squeegees specifically includes the steps of:
firstly, converting image information obtained by a terahertz wave transceiver into an electric signal;
then, denoising, smoothing and converting the electric signal to strengthen the boundary characteristic of a scraper in the image;
secondly, extracting and selecting characteristics, and extracting boundary information of the obtained scraper;
finally, a classifier design is carried out, so that the distance L between the two scrapers is obtained.
Has the advantages that: the invention provides a scraper conveyor chain tension monitoring system, which can monitor the tension of a scraper conveyor without damaging the scraper chain, realize the nondestructive monitoring of the scraper chain tension, judge the running state of the scraper conveyor based on tension data and provide a basis for equipment to adjust running parameters; meanwhile, according to the image presented by the terahertz imaging system, the vibration condition of the scraper chain is observed through visual inspection, and when the amplitude of the shaking of the scraper chain exceeds the width of the chain link, the running state of the scraper is unstable, and the running conditions of the scraper and a coal mining machine need to be adjusted in time.
Drawings
FIG. 1 is a schematic structural diagram of the present invention.
Fig. 2 is a schematic view of fig. 1 with the dust cover partially removed.
Fig. 3 is a view from direction ii in fig. 1.
Fig. 4 is a flowchart of a terahertz imaging unit.
FIG. 5 is a flow chart of an embodiment of the present invention.
The figure includes: 1. coal mining machine, 2, dust cover, 3, support unit, 4, middle groove, 5, scraper chain, 6, scraper, 7, Hertz wave transceiver, 8, motor, 9, coupling, 10 and powder scraping mechanism.
Detailed Description
The invention will be further explained below with reference to the drawings.
As shown in fig. 1, 2 and 3, a bracket 3 is fixed on a coal mining machine 1 through bolts, the other end of the bracket 3 is connected with a terahertz wave transceiver 7, a signal of the terahertz wave transceiver 7 is transmitted to an external board level circuit and a notebook through a wireless transmitter arranged on the bracket 3, a dust cover 2 is arranged on the outer side of the terahertz wave transceiver 7, a dust scraping device 10 is connected on the outer side of the dust cover 2 and is controlled to rotate by a stepping motor 8, and wires of the dust cover 2 and the dust scraping device 10 are connected to the outside through the bracket 3.
When the system is installed, the side of the dust cover 2 closest to the coal mining machine 1 is sleeved on the bracket 3, and the connecting part is welded; secondly, a terahertz wave transceiver 7 is installed and fixed on the bracket 3 by using a bolt; then the four walls of the dust cover 2 are installed, the periphery of the dust cover is welded with the surface which is installed in advance, and finally the side farthest away from the coal mining machine 1 is installed and fixed by bolts, so that the dust cover is convenient to disassemble during maintenance.
The main body of the dust cover 2 is made of a titanium alloy material, the bottom surface of the dust cover is made of a modified polypropylene material, the two materials have the characteristics of high strength, high temperature resistance, corrosion resistance and the like, the inner terahertz wave transceiver 7 can be protected from being influenced by external dust, falling coal blocks, corrosive liquid and the like, and normal work of the terahertz wave transceiver is guaranteed.
The dust scraping device 10 is controlled to rotate by a stepping motor 8, and the two are connected by a coupler 9. The selected stepping motor has the characteristics of high precision and forward and reverse rotation, the stepping motor is arranged on an external controller to pass through three processes of forward rotation, reverse rotation and stop, and when the speeds of the stepping motors are different, the running speed of the dust scraping device is changed; when the stop time is different, the running frequency of the device is changed, so that dust scraping movement with different frequencies and speeds can be realized by controlling the speed and the running of the motor, and the normal and efficient running of the terahertz imaging unit is ensured.
A layer of soft plastic convenient to replace is added on the working surface of the dust scraping device 10, so that dust on the dust cover is completely scraped.
As shown in fig. 4, the terahertz imaging unit transmits and receives signals through the terahertz transceiver, analyzes and processes the received information, and finally displays images of the blade and the chain on a computer.
As shown in fig. 5, the monitoring method includes the steps of:
and selecting the scraper chain with the distance between the two scrapers to perform a tensile test on a fatigue testing machine, and measuring the force-deformation curve of the scraper chain and the deformation of the scraper chain when the scraper chain is broken S0.
And (3) shooting a video of the scraper conveyor in the running process by using a terahertz imaging unit.
And selecting a photo at intervals of t, identifying the distance L between the two scrapers through an image identification system, and subtracting the initial distance L0 to obtain the deformation S of the scraper chain.
And (5) corresponding the S to the force-deformation curve of the scraper chain to obtain the tension F of the scraper chain.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be construed as the protection scope of the present invention.